The present invention relates to an apparatus and a method for multiplexing serial data into horizontal blanking portions of video data to be transmitted, involving little data delay and doing away with complicated control procedures. More particularly, the invention relates to a video camera system incorporating the same apparatus and method.
When any communication command furnished in serial data is to be multiplexed into horizontal blanking portions of video data (e.g., 8-bit parallel data), the serial communication command is first converted conventionally to parallel data reaching the CPU (central processing unit) or the like. It is in the form of parallel data that the communication command is multiplexed into the horizontal blanking period of video data.
If the transmission rate of serial communication command data is lower than the horizontal blanking rate (about 15 kHz), the conventional method above necessarily entails a delay equivalent to the serial-parallel conversion time for multiplexing.
For example, consider 11-bit serial communication command data composed of a start bit (1 bit), data (8 bits), a parity bit (1 bit) and a stop bit (1 bit). In such a case, to perform the conventional serial-parallel conversion requires waiting for the entire 11-bit data to be received. If the rate of serial communication command data is 9,600 bps, the delay amounts to approximately 17 horizontal periods. Where the data is to be multiplexed into horizontal blanking portions in each of the 17 horizontal periods, complicated control procedures are needed illustratively to determine which blanking portion is to have the data multiplexed therein and which portion is not to.
It is therefore an object of the present invention to provide an apparatus and a method for multiplexing serial data involving little data delay and without complicated control procedures for multiplexing.
In carrying out the invention and according to a first aspect thereof, there is provided a data transmission apparatus comprising: first data inputting means for inputting serial data transmitted at a first rate; second data inputting means for inputting video data; data sampling means for generating resampled data by sampling the serial data input via the first data inputting means, the sampling being performed by use of a clock signal at a second rate higher than the first rate; data extracting means for extracting a predetermined number of resampled data from the resampled data output by the data sampling means in each of the horizontal periods of the video data; data multiplexing means for generating multiplexed data by multiplexing into horizontal blanking portions of the video data the predetermined number of resampled data extracted by the data extracting means; and data outputting means for outputting the multiplexed data generated by the data multiplexing means.
According to a second aspect of the invention, there is provided a data reception apparatus comprising: data inputting means for inputting multiplexed data acquired by multiplexing control data into horizontal blanking portions of video data; data separating means for separating the video data and the control data from the multiplexed data; data defining means for defining definite data from the control data separated by the data separating means; first data outputting means for outputting the definite data defined by the data defining means; and second data outputting means for outputting the video data separated by the data separating means.
According to a third aspect of the invention, there is provided a data transmission apparatus comprising: first data inputting means for inputting serial data transmitted at a first rate; second data inputting means for inputting video data; data sampling means for generating resampled data by sampling the serial data input via the first data inputting means, the sampling being performed by use of a clock signal at a second rate higher than the first rate; data extracting means for extracting a predetermined number of resampled data from the resampled data output by the data sampling means in each of the horizontal periods of the video data; data multiplexing means for generating multiplexed data by multiplexing into horizontal blanking portions of the video data the predetermined number of resampled data extracted by the data extracting means as control data; data transmitting means for transmitting the multiplexed data; data separating means for separating the video data and the control data from the multiplexed data transmitted by the data transmitting means; data defining means for defining definite data from the control data separated by the data separating means; first data outputting means for outputting the definite data defined by the data defining means; and second data outputting means for outputting the video data separated by the data separating means.
According to a fourth aspect of the invention, there is provided a video camera comprising: signal processing means for outputting video data; data inputting means for inputting serial data transmitted at a first rate; data sampling means for generating resampled data by sampling the serial data input via the data inputting means, the sampling being performed by use of a clock signal at a second rate higher than the first rate; data extracting means for extracting a predetermined number of resampled data from the resampled data output by the data sampling means in each of the horizontal periods of the video data; data multiplexing means for generating multiplexed data by multiplexing into horizontal blanking portions of the video data the predetermined number of resampled data extracted by the data extracting means; and data outputting means for outputting the multiplexed data generated by the data multiplexing means.
According to a fifth aspect of the invention, there is provided a video camera comprising: data inputting means for inputting multiplexed data acquired by multiplexing control data into horizontal blanking portions of video data; data separating means for separating the video data and the control data from the multiplexed data; data defining means for defining definite data from the control data separated by the data separating means; first data outputting means for outputting the definite data defined by the data defining means; and second data outputting means for outputting the video data separated by the data separating means.
According to a sixth aspect of the invention, there is provided a video camera comprising: signal processing means for outputting video data; first data inputting means for inputting serial data transmitted at a first rate; data sampling means for generating resampled data by sampling the serial data input via the first data inputting means, the sampling being performed by use of a clock signal at a second rate higher than the first rate; data extracting means for extracting a predetermined number of resampled data from the resampled data output by the data sampling means in each of the horizontal periods of the video data; data multiplexing means for generating multiplexed data by multiplexing into horizontal blanking portions of the video data the predetermined number of resampled data extracted by the data extracting means; first data outputting means for outputting the multiplexed data generated by the data multiplexing means; second data inputting means for inputting multiplexed data acquired by multiplexing control data into horizontal blanking portions of the video data; data separating means for separating the video data and the control data from the multiplexed data input via the second data inputting means; data defining means for defining definite data from the control data separated by the data separating means; second data outputting means for outputting the definite data defined by the data defining means; and third data outputting means for outputting the video data separated by the data separating means.
According to a seventh aspect of the invention, there is provided a camera control unit comprising: first data inputting means for inputting serial data transmitted at a first rate; second data inputting means for inputting video data; data sampling means for generating resampled data by sampling the serial data input via the first data inputting means, the sampling being performed by use of a clock signal at a second rate higher than the first rate; data extracting means for extracting a predetermined number of resampled data from the resampled data output by the data sampling means in each of the horizontal periods of the video data; data multiplexing means for generating multiplexed data by multiplexing into horizontal blanking portions of the video data the predetermined number of resampled data extracted by the data extracting means; and data outputting means for outputting the multiplexed data generated by the data multiplexing means.
According to an eighth aspect of the invention, there is provided a camera control unit comprising: data inputting means for inputting multiplexed data acquired by multiplexing control data into horizontal blanking portions of video data; data separating means for separating the video data and the control data from the multiplexed data; data defining means for defining definite data from the control data separated by the data separating means; first data outputting means for outputting the definite data defined by the data defining means; and second data outputting means for outputting the video data separated by the data separating means.
According to a ninth aspect of the invention, there is provided a camera control unit comprising: first data inputting means for inputting serial data transmitted at a first rate; second data inputting means for inputting video data; data sampling means for generating resampled data by sampling the serial data input via the first data inputting means, the sampling being performed by use of a clock signal at a second rate higher than the first rate; data extracting means for extracting a predetermined number of resampled data from the resampled data output by the data sampling means in each of the horizontal periods of the video data; data multiplexing means for generating multiplexed data by multiplexing into horizontal blanking portions of the video data the predetermined number of resampled data extracted by the data extracting means; first data outputting means for outputting the multiplexed data generated by the data multiplexing means; third data inputting means for inputting multiplexed data acquired by multiplexing control data into horizontal blanking portions of the video data; data separating means for separating the video data and the control data from the multiplexed data input via the third data inputting means; data defining means for defining definite data from the control data separated by the data separating means; second data outputting means for outputting the definite data defined by the data defining means; and third data outputting means for outputting the video data separated by the data separating means.
According to a tenth aspect of the invention, there is provided a video camera system comprising a video camera, data transmitting means and a camera control unit. The video camera includes: signal processing means for outputting video data; first data inputting means for inputting serial data transmitted at a first rate; data sampling means for generating resampled data by sampling the serial data input via the first data inputting means, the sampling being performed by use of a clock signal at a second rate higher than the first rate; data extracting means for extracting a predetermined number of resampled data from the resampled data output by the data sampling means in each of the horizontal periods of the video data; data multiplexing means for generating multiplexed data by multiplexing as control data the predetermined number of resampled data extracted by the data extracting means into horizontal blanking portions of the video data; and first data outputting means for outputting the multiplexed data generated by the data multiplexing means. The data transmitting means transmits the multiplexed data output by the first data outputting means of the video camera. The camera control unit includes: second data inputting means for inputting the multiplexed data transmitted by the data transmitting means; data separating means for separating the video data and the control data from the multiplexed data input via the second data inputting means; data defining means for defining definite data from the control data separated by the data separating means; second data outputting means for outputting the definite data defined by the data defining means; and third data outputting means for outputting the video data separated by the data separating means.
According to an eleventh aspect of the invention, there is provided a video camera system comprising a camera control unit, data transmitting means and a video camera. The camera control unit includes: first data inputting means for inputting serial data transmitted at a first rate; second data inputting means for inputting video data; data sampling means for generating resampled data by sampling the serial data input via the first data inputting means, the sampling being performed by use of a clock signal at a second rate higher than the first rate; data extracting means for extracting a predetermined number of resampled data from the resampled data output by the data sampling means in each of the horizontal periods of the video data; data multiplexing means for generating multiplexed data by multiplexing as control data the predetermined number of resampled data extracted by the data extracting means into horizontal blanking portions of the video data; and first data outputting means for outputting the multiplexed data generated by the data multiplexing means. The data transmitting means transmits the multiplexed data output by the first data outputting means of the camera control unit. The video camera includes: third data inputting means for inputting the multiplexed data transmitted by the data transmitting means; data separating means for separating the video data and the control data from the multiplexed data input via the third data inputting means; data defining means for defining definite data from the control data separated by the data separating means; second data outputting means for outputting the definite data defined by the data defining means; and third data outputting means for outputting the video data separated by the data separating means.
According to a twelfth aspect of the invention, there is provided a data transmission method comprising the steps of: inputting serial data transmitted at a first rate; inputting video data; generating resampled data by sampling the input serial data by use of a clock signal at a second rate higher than the first rate; extracting a predetermined number of resampled data from the resampled data generated in each of the horizontal periods of the video data; generating multiplexed data by multiplexing the extracted predetermined number of resampled data into horizontal blanking portions of the video data; and outputting the multiplexed data.
According to a thirteenth aspect of the invention, there is provided a data reception method comprising the steps of: inputting multiplexed data acquired by multiplexing control data into horizontal blanking portions of video data; separating the video data and the control data from the multiplexed data; defining definite data from the control data separated from the multiplexed data; outputting the definite data defined by the defining step; and outputting the video data separated from the multiplexed data.
According to a fourteenth aspect of the invention, there is provided a data transmission method comprising the steps of: inputting serial data transmitted at a first rate; inputting video data; generating resampled data by sampling the input serial data by use of a clock signal at a second rate higher than the first rate; extracting a predetermined number of resampled data from the resampled data generated in each of the horizontal periods of the video data; generating multiplexed data by multiplexing as control data the extracted predetermined number of resampled data into horizontal blanking portions of the video data; outputting the multiplexed data; transmitting the multiplexed data; separating the video data and the control data from the multiplexed data transmitted by the transmitting step; defining definite data from the control data separated from the multiplexed data; outputting the definite data defined by the data defining step; and outputting the video data separated from the multiplexed data.
Serial data is sampled by use of a clock signal having a clock rate higher than the transmission rate of the serial signal. The sampling process provides a plurality of resampled data in each one-bit period of the serial data. Even if the transmission rate of the serial data is lower than the horizontal blanking rate of video data, at least one item of resampled data is made available in each of the horizontal periods of the video data. In this state, a predetermined number of resampled data are selected from the resampled data obtained in each of the horizontal periods of the video data. The selected predetermined number of resampled data are multiplexed into the horizontal blanking portions of the video data when transmitted. Because the inventive method does not involve subjecting the serial data to serial-parallel conversion and multiplexing the converted data into the horizontal blanking portions of the video data, there is a minimum of data delay. With a predetermined number of data constantly multiplexed into each horizontal blanking portion of the video data, the inventive method eliminates the need for complicated control procedures for determining which horizontal blanking portion is to have data multiplexed therein and which portion is not to.